Mumps virus as a potential oncolytic agent

ABSTRACT

This document relates to methods and materials for virotherapy. For example, this document provides methods and materials for treating cancer using a recombinant mumps virus as an oncolytic agent.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 62/075,099, filed June 12, 2015. The disclosure of the prior application is incorporated by reference in its entirety.

BACKGROUND 1. Technical Field

This document relates to methods and materials for virotherapy. For example, this document provides methods and materials for treating cancer using a recombinant mumps virus as an oncolytic agent.

2. Background Information

Advanced metastatic cancers are basically incurable from having developed into a heterogeneous population with multiple ways to override the normal growth controls. Therefore it is unlikely that therapeutic attack on a single molecular target will have much effect and therapeutics (e.g., chemotherapy combinations, radiotherapies) often select resistance from the tumors heterogeneous population.

SUMMARY

Mumps virotherapy is extremely safe with virulent Urabe strain virus. Mumps virus (MuV) has significant oncolytic activity against variety of human cancers. Mumps treatment induces significant anti-tumor immunity indicating that MuV can be a potential candidate for immune therapy.

As described herein, a recombinant MuV can infect human tumor cells and exhibit oncolytic efficacy both in in vitro and in vivo. This document describes isolates of a MuV having oncolytic activity. This document also provides methods of making and using the oncolytic mumps virus. For example, the document provides methods of treating cancer by administering a recombinant MuV.

In general, one aspect of this document features a MuV (e.g., a recombinant MuV). The recombinant MuV can have oncolytic anti-cancer activity. The recombinant MuV can be a replication competent MuV. The recombinant MuV can include a modification in an RNA polymerase large (L) subunit coding sequence (e.g., an A to C substitution at nucleotide 13328). The modified RNA polymerase large (L) subunit coding sequence can encode a modified RNA polymerase large (L) subunit protein (e.g., an RNA polymerase large (L) subunit protein having an N to H substitution at amino acid 1631).

In another aspect, this document features a method for treating a patient having cancer. The method can include, or consist essentially of, administering to the patient a recombinant MuV having oncolytic anti-cancer activity. The cancer can be a blood cancer (e.g., leukemia, lymphoma, or myeloma). The blood cancer can be myeloma. The cancer can be a carcinoma (e.g., prostate cancer, breast cancer, hepatocellular carcinoma, lung cancer, or colorectal carcinoma). The carcinoma can be colorectal carcinoma. The recombinant MuV can be a replication competent MuV. The recombinant MuV can include a modification in an RNA polymerase large (L) subunit coding sequence (e.g., an A to C substitution at nucleotide 13328). The modified RNA polymerase large (L) subunit coding sequence can encode a modified RNA polymerase large (L) subunit protein (e.g., an RNA polymerase large (L) subunit protein having an N to H substitution at amino acid 1631). The method also can include administering ruxolitinib.

In another aspect, this document features an expression construct comprising a nucleotide sequence encoding a recombinant MuV having oncolytic anti-cancer activity. The recombinant MuV can be a replication competent MuV. The recombinant MuV can include a modification in an RNA polymerase large (L) subunit coding sequence (e.g., an A to C substitution at nucleotide 13328). The modified RNA polymerase large (L) subunit coding sequence can encode a modified RNA polymerase large (L) subunit protein (e.g., an RNA polymerase large (L) subunit protein having an N to H substitution at amino acid 1631).

In another aspect, this document features a method for treating a patient having cancer. The method includes, or consists essentially of, administering to the patient an expression construct including a nucleotide sequence encoding a recombinant MuV having oncolytic anti-cancer activity. The cancer can be a blood cancer (e.g., leukemia, lymphoma, or myeloma). The blood cancer can be myeloma. The cancer can be a carcinoma (e.g., prostate cancer, breast cancer, hepatocellular carcinoma, lung cancer, or colorectal carcinoma). The carcinoma can be colorectal carcinoma. The recombinant MuV can be a replication competent MuV. The recombinant MuV can include a modification in an RNA polymerase large (L) subunit coding sequence (e.g., an A to C substitution at nucleotide 13328). The modified RNA polymerase large (L) subunit coding sequence can encode a modified RNA polymerase large (L) subunit protein (e.g., an RNA polymerase large (L) subunit protein having an N to H substitution at amino acid 1631). The method also can include administering ruxolitinib.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic showing the procedure used to identify MuV isolates from the original mumps virus, and the generated recombinant MuV.

FIG. 2 shows MuV isolates in the tcMuV-U stock.

FIG. 3 shows safety of MuV virotherapy.

FIG. 4 shows oncolytic activity of MuV in human cancers.

FIGS. 5A-5B show rescue of recombinant mumps viruses Urabe strain (rMuV-UC). A. Rescue of rMuV-UC-GFP infectious virus in BHK cells and further propagation of the same virus in Vero cells visualized by fluorescent microscopy. B. Mumps virus wild-type and rescued virus rMuV6 UC-GFP were compared for their growth potential in Vero cell in multi-step growth curve. Cells were infected with MOI of 0.1, supernatants and cell pellets were collected at different time intervals and titered in vero cells using standard plaque assay. Left panel shows virus titer of cell free supernatants and right panel shows virus titer of cell associated virus.

FIGS. 6A-6E show characterization of the replication and transgene expression of the recombinant mumps viruses. A. Schematic diagram of various constructs of mumps virus expressing foreign genes. B. Growth curve of various recombinant mumps viruses in Vero cells after infection at M.O.I. 0.1. C. Luciferase assay demonstrating the expression of LUC transgene by the rMuV14 UC-LUC in infected cells compared to only background LUC expression by the original MuV15 UC virus isolate. D. Measurement and comparison of activity of NIS produced by rMuV-UC16 NIS and wild-type MuV-UC-wt. E. Measurement of secreted mIFN-β in the supernatant of rMuV-UC-mIFNβ and MuV-UC infected vero cells by ELISA.

FIGS. 7A-7C show rMuV-UC-GFP replication in tumor cell lines. A.

Human cancer cell lines were infected with mumps virus at MOI of 10 and images were taken 5 days of post-infection. B. Mouse cancer cell lines were infected with mumps virus at MOI of 10 and images were taken 5 days post-infection. C. Selected cell lines were infected with MOI of 1.0 and supernatants were collected at indicated time points and titered in vero cells.

FIG. 8 shows a comparison of mumps viruses for the efficacy and growth potential in selected cell lines. (A-C) CT-26-LacZ, N2A and Kas 6/1 cell lines were infected with MuV-UC-WT, MuV-UC-GFP and MuV-UC-L13328 at indicated MOI. Cell viability was measured on day 7 by MTS Cell Proliferation Assay. (D) Vero cells were infected with MOI of 0.1, supernatants were collected at different time intervals and titered in vero cells using standard plaque assay.

FIGS. 9A-9C show infectivity of rMuV-UC-GFP in rat cancer cells. A. Rat glioma cells C6 and RG2 were infected at MOI 0.1 and compared with Vero cells. The fluorescent images were taken at indicated time points. B. Vero, RG2 and C6 cells were infected with mumps virus at 0.1 MOI. Supernatants were collected at indicated time points and were titered in Vero cells. C. Cell viability assay for C6 and RG2 cells infected with mumps virus.

FIG. 10 shows the effect of a Janus kinase inhibitor on mumps virus infectivity. Selected tumor cells lines were treated with Ruxolitinib, a Janus kinase inhibitor, at the indicated doses. After 48 hours the treated and control cells were infected with rMuV-UC-GFP mumps virus (M.O.I. 10). Fluorescent images were taken 5 days post-infection.

FIGS. 11A-11F show oncolytic efficacy of mumps viruses in the mouse CT-26-LacZ colon carcinoma tumor model. Balb/c mice (n=5) were implanted with 5×10⁶ CT-26-LacZ cells subcutaneously. Once the tumor volume reached 0.2 to 0.5 mm³, mice were treated with saline or mumps viruses (10⁶−10⁷ PFU) administered intravenously through by tail vein: (A) MuV-UC-wt (10⁷), (B) rMuV-UC-GFP-10⁶; (C) rMuV-UC-GFP-10⁷; (D) rMuV-UC-Luc (10⁷); or (E) saline. Tumor size was measured using handheld calipers three times a week. (F) Kaplan-Meier survival curves for the mice are shown in the survival curve. *, P=0.0072 rMuV-UC-wt vs Saline; P=0.1316 rMuV-UC-Luc vs Saline.

FIGS. 12A-12D show in vitro oncolytic efficacy of MuV-UC-GFP. Panel of mouse and human cancer cell lines were infected with indicated MOI of MuV-UC-GFP. Cell viability was measured on day 7 by MTS Cell Proliferation Assay.

FIGS. 13A-13E show oncolytic efficacy of mumps virus in the mouse N2A neuroblastoma tumor model. A/J mice (4 weeks old, n=7) bearing subcutaneous N2A tumors were treated with a single dose (1×10⁷) administered intravenously through by tail vein: (A) MuV-UC-wt; (B) rMuV-UV-L13328-GFP; (C) rMuV-UC-LUC; (D) or saline. Tumor size was measured using handheld calipers three times a week. (E) Kaplan-Meier survival curves for the mice are shown in the survival curve.

FIGS. 14A-14E show oncolytic efficacy of mumps viruses infection in human myeloma model. NCr nude mice (4 weeks old; n=5) bearing subcutaneous Kas6/1 myeloma tumors were treated with a single intravenous dose (1×10⁷ pfu) of (A) MuV-UC-wt; (B) rMuV-UC-LUC; or (C) rMuV21 UC-L13328-GFP; (D) control saline. Tumor size was measured by serial caliper measurements. (E) Kaplan-Meier survival curves for the mice are shown in the survival curve.

FIG. 15 shows immunohistochemical staining of Kas6/1 tumors. Kas6/1 tumors were harvested at 7 day and 12 day post-treatment, sectioned and immunohistochemistry (IHC) staining was carried out using mumps polyclonal antibodies; mumps virus antigen (red) and cell nuclei (Hoechst /blue). Magnification, 40X.

FIG. 16 shows the Urabe mumps virus sequence (SEQ ID NO:1) encoding the NP protein (SEQ ID NO:2), the P protein (SEQ ID NO:3), the V protein (SEQ ID NO:4), the I protein (SEQ ID NO:5), the M protein (SEQ ID NO:6), the F protein (SEQ ID NO:7), the SH protein (SEQ ID NO:8), the HN protein (SEQ ID NO:9), the L protein (SEQ ID NO:10). See, NCBI Accession No: AF314558.

DETAILED DESCRIPTION

This document provides methods and materials for treating cancer. For example, this document provides methods and materials for using a MuV to treat cancer. In some cases, a MuV can be used to reduce the number of cancer cells.

An oncolytic virus is a virus that preferentially infects and kills cancer cells. Oncolytic viruses are thought not only to cause direct destruction of cancer cells, but also to stimulate host anti-cancer immune responses.

Oncolytic virotherapy is an emerging cancer treatment that seeks to use viruses that have evolved to exploit some of the same pathways that cancer cells activate during malignant progression to kill these cells. In addition, in a second arm of attack, the combination of cancer cell destruction by viruses may trigger a unique immune response from the combination of virus induced danger signals and the heterogeneous antigenic variation of the cancer cells. A wide variety of viruses from very different virus families are currently being explored as cancer therapeutics. As with chemotherapies and radiotherapies, we can expect that each oncolytic virus may have an optimal therapeutic effect only on certain cancer types. Treating patients with combinations of oncolytic viruses as well as in combination with chemotherapies and radiotherapies will offer therapeutics with vastly different modes of action that will work together to reduce tumor cell escape.

This disclosure provides a MuV (e.g., an Urabe strain MuV) having oncolytic anti-cancer activity. A MuV provided herein can be a recombinant MuV. A MuV provided herein can be a MuV isolate. In some cases, a MuV provided herein can be a replication competent MuV. A MuV provided herein can include one or more modifications from a wild type MuV. In some cases, a MuV provided herein can include one or more modifications from the Urabe strain of MuV. An Urabe strain of MuV can have a sequence set forth in, for example, National Center for Biotechnology Information (NCBI) Accession No: AF314558 (see, e.g., Version AF314558.1; GI:14325886). A MuV provided herein can include one or more modifications in a non-coding region of a MuV and/or one or more modifications in any MuV coding sequence. A MuV provided herein can include one or more modifications in an encoded protein. Examples of MuV proteins include, for example, nucleocapsid proteins (NP), matrix (M) proteins, fusion (F) proteins, hemagglutinin-neuraminidase (HN) proteins, large (L) subunit protein of the RNA polymerase, or phosphoprotein (P) subunit of the RNA polymerase). A MuV provided herein can include one or more modifications in the large (L) subunit protein of the RNA polymerase. For example, a MuV provided herein can include a substitution (e.g., an A to C substitution) at nucleotide 13328 (nt13328) of the L coding sequence resulting in an N to H substitution at amino acid 1631 in the L subunit protein of the RNA polymerase. Modifications can include any of a variety of changes, and include changes to the genome of the virus. Exemplary nucleic acid modifications include substitutions, truncations, insertions, and deletions. In some cases, a MuV can be modified by one or more substitutions relative to the wild type Urabe strain of MuV. Exemplary modifications include, for example, the nucleotide substitutions and resulting amino acid changes set forth in Tables 1 - 2. Modifications shown in Tables 1 - 2 are relative to the Urabe mumps virus sequence in NCBI Accession No: AF314558.

Also included are MuV sequences having at least 80% (e.g., at least 85%; at least 90%; at least 92%; at least 95%; at least 98%; and at least 99%) sequence identity to the recombinant MuV provided herein provided the sequence maintains oncolytic activity.

This document also provides expression vectors that can carry a MuV provided herein into another cell (e.g., a cancer cell), where it can be replicated and/or expressed. An expression vector, also commonly referred to as an expression construct, is typically a plasmid or vector having an enhancer/promoter region controlling expression of a specific nucleotide sequence. When introduced into a cell, the expression vector utilizes cellular protein synthesis machinery to produce the virus in the cell. The expression vector of the instant disclosure includes a nucleotide sequence encoding a MuV provided herein (e.g., a MuV having oncolytic anti-cancer activity). An expression vector including a MuV provided herein can also include a nucleotide sequence encoding a detectable label. Examples of detectable label are well known in the art and can include green fluorescent protein, and luciferase. An expression vector including a MuV provided herein can also include a nucleotide sequence encoding another useful peptide. Examples of other useful peptides include, without limitation, transport peptides (e.g., sodium/iodide symporter (NIS) and nuclear localization sequence (NLS), immune modulators (e.g., interleukins, cytokines, and interferons such as interferon beta and interferon gamma), and therapeutic peptides.

This document also provides methods and materials for using a MuV provided herein. In some cases, a MuV provided herein can used for treating a patient having cancer. For example, a MuV provided herein can be administered to any appropriate patient to reduce the number of cancer cells in the mammal (e.g., suppress and/or delay tumor growth) and/or to increase survival of the mammal.

Methods for treating a patient having cancer can include administering to the patient a MuV provided herein. Any appropriate patient having cancer can be treated as described herein. For example, humans, non-human primates, monkeys, horses, bovine species, porcine species, dogs, cats, mice, and rats having cancer can be treated for cancer as described herein. In some embodiments, a human having cancer can be treated. In addition, a mammal having any particular type of cancer can be treated as described herein. For example, human with myeloma can be treated for cancer.

The method may be useful for treating any type of cancer. In some embodiments, the cancer can be a blood cancer. For example, the cancer can be, without limitation, a leukemia (cancer in the blood and bone marrow), a lymphoma (cancer in the lymphatic system), and/or myeloma (cancer of the plasma cells). In some embodiments, the cancer can be myeloma. In some embodiments, the cancer can be a carcinoma (cancer derived from epithelial cells). For example, the cancer can be, without limitation, prostate cancer, breast cancer, hepatocellular carcinoma, renal cell carcinoma, ovarian cancer, cervical cancer, lung cancer, colorectal carcinoma, colon cancer, neuroblastoma, glioma, plasmacytoma, and/or mesothelioma. In some embodiments, the cancer can be colorectal carcinoma.

Methods for treating a patient having cancer can include identifying the patient as having cancer. Examples of methods for identifying the patient as having cancer include, without limitation, physical examination, laboratory tests (e.g., blood and/or urine), biopsy, imaging tests (e.g., X-ray, PET/CT, MRI, and/or ultrasound), nuclear medicine scans (e.g., bone scans), endoscopy, and/or genetic tests. Once identified as having cancer, the patient can be administered or instructed to self-administer a MuV provided herein.

Methods for treating a patient having cancer also can include one or more additional treatments such as surgery, chemotherapy, radiation therapy, immunotherapy, targeted therapy, hormone therapy, and/or a Janus kinase inhibitor (e.g., Ruxolitinib). In some cases, a MuV provided herein can be formulated together with one or more additional treatments (e.g., chemotherapy, radiation therapy, and/or Ruxolitinib) to form a single composition. In some cases, one or more additional treatments can be provided to a patient in a separate composition; one containing a MuV provided herein, and one containing, for example, Ruxolitinib. In cases, where a MuV provided herein and one or more additional treatments are provided separately, the administration of a MuV provided herein can be in any order relative to the administration of one or more additional treatments. For example, a MuV provided herein can be administered to a patient prior to, concurrent with, or following administration of one or more additional treatments to the patient.

A MuV can be administered by any route, e.g., IV, intramuscular, SC, oral, intranasal, inhalation, transdermal, and parenteral. In some embodiments, a MuV provided herein can be administered by IV.

Also included the instant disclosure are pharmaceutical compositions including the MuV described herein, as well as pharmaceutical compositions including the expression construct described herein. For example, a MuV or an expression vector can be formulated into a pharmaceutically acceptable composition for administration to a patient having, or at risk of having, cancer. In some embodiments, a MuV or an expression construct can be formulated together with one or more pharmaceutically acceptable carriers (additives) and/or diluents. A pharmaceutical composition can be formulated for administration in solid or liquid form including, without limitation, sterile solutions, suspensions, sustained-release formulations, tablets, capsules, pills, powders, and granules.

Pharmaceutically acceptable carriers, fillers, and vehicles that may be used in a pharmaceutical composition described herein include, without limitation, ion exchangers, alumina, aluminum stearate, lecithin, serum proteins, such as human serum albumin, buffer substances such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes, such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-based substances, polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycol and wool fat.

In some embodiments the pharmaceutical composition is administered as a vaccine. The vaccine may prophylactic or therapeutic.

The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims.

EXAMPLES Example 1 -Identification of MuV Isolates

To bring this work up to today's clinical standards for use in humans, a thorough characterization of a tcMuV-U pool was performed. Briefly, the Urabe strain of MuV (MuV-U) was plaque purified and sequenced, and was subjected to a reverse genetics system to identify MuV isolates having oncolytic activity as shown in FIG. 1.

The virus was amplified using cells grown in culture, primary human embryonic kidney (HEK) cells, and then this original Urabe mumps virus seed stock (tcMu V-U) underwent additional rounds of amplification in HEK cells and/or human amnion cells (A V3 cells) to generate virus stocks used in three different clinical trials (Asada, 1974 Cancer 34:1907-28; Okuno et al., 1978 Biken J. 21:37-49; Shimizu et al., 1988 Cancer Detect Prey. 12:487-95). The tcMuV-U in these stocks is an undefined mixture of isolates that have changed and possibly undergone mutations that have attenuated the wild-type phenotype as they have been passaged in cultured cells. The nucleotide sequence of the tcMuV-U virus mixture was determined from cDNAs produced from the viruses negative strand RNA genomes and are reported as the predominant sequence (e.g., average sequence) from the group (Table 3). Modifications shown in Table 3 are relative to the Urabe mumps virus sequence in NCBI Accession No: AF314558.

Several nucleotides read as a mixture of different viruses (e.g., bases 3670, 5584 and 14494) demonstrating the tcMuV-U virus stock to be a mixture. The SIPAR attenuated Urabe vaccine strain (NCBI Accession No. AF314558.1) was used to compare the tcMuV-U sequences. Quite a few candidate attenuated vaccine strains were derived from the original Urabe MuV sample by various forms of culture. The unique point of the tcMuV-U stock is that a minimal amount of passaging in human cells was done to try and keep the virus from changing and attenuating too much.

The mixture of MuV isolates in the original tcMuV-U stock by identifying major strains was genetically defined by initially producing isolates of individual viruses by limiting dilution (FIG. 2).

Virus stocks from twelve individual viruses were produced, 1-A to 1-L, and the nucleotide sequence determined from cDNAs produced from the negative strand RNA genomes of each virus stock (Table 2).

After analysis of the genome sequences of these twelve individual isolates and the overall tcMu V-U mixture, it was determined that there were four major groups of different isolates by genome sequences, A, B, C and I. Each of these isolates was purified by limiting dilution a total of three times, and a representative one or two virus stocks produced for each: 1-A-3, 1-B-3a, 1-B-3b, 1-C-3 and 1-I-3. 16 unique tcMuV-U genome sequences were identified. The nucleotide sequences were determined from cDNAs of each now 3X purified virus isolate and compared to the first sequence (Table 3).

Example 2 -Mumps Virus as an Oncolytic Agent

The oncolytic potential of Urabe strain of MuV was explored. MuV isolates identified in Example 1 were used to generate recombinant viruses which were evaluated in in vitro cancer models as shown in FIG. 1.

MuV isolates were administered to cancer cells. A MuV growth curve was established and a cytotoxicity assay was performed.

MuV was extremely safe with virulent Urabe strain virus (FIG. 3). MuV had significant oncolytic activity against variety of human cancers (FIG. 4).

These results demonstrate that MuV can induce significant anti-tumor immunity indicating that MuV can be a potential candidate for immune therapy.

Example 3 -Recombinant Mumps Virus as a Cancer Therapeutic Agent METHODS AND MATERIALS

Viruses and cells. Mumps virus Urabe strain (MuV-U) was originally collected from saliva of a child with mumps symptoms in Japan, isolated after replication in cultured primary human embryonic kidney cells (HEK), and then the virus was amplified in HEK to produce a seed stock (Asada, 1974 Cancer 34:1907-1928). This seed stock then went through an unknown number of amplifications on HEK and/or human amnion cells (AV3) to produce virus lots for several clinical trials in Japan in the 1970′s and 1980′s. An aliquot of the MuV-U stock used in these clinical trials was obtained from Dr. Koichi Yamanishi (Osaka University). The Viral Vector Production Laboratory at the Mayo Clinic isolated individual virus plaques from this stock using limited dilution in Vero cells, and determined the nucleotide sequences from RT-PCR products from the viral RNA genomes.

The cell lines used in this study were obtained from American Type Culture Collection (ATCC), Manassas, Va. and were maintained in medium recommended by ATCC in 5% CO₂. The following cell lines were used in this study; BHK, baby hamster kidney cell line, Vero-African green monkey kidney cell line, kas6/1, JJN3, MM1, RPMI6225-human myeloma, ARH-77-plasma cell leukemia, Skov3-ovarian cancer, A549-lung adenocarcinoma, Hela-cervical cancer; mouse cancer cell lines: N2A-neuroblastoma, CT-26-colon carcinoma, LLC- lung carcinoma, NB41A3-neuroblastoma, MPC11-plasmacytoma, 4T1-breast cancer, AB12-mesothelioma, EL-4-lymphoma, RENCA-renal carcinoma, XS-63-myeloma; C6 and RG2-rat glioma. The oncolytic activities of the mumps virus infections were quantitated using MTS Cell Proliferation Colorimetric Assay Kit (BioVision Inc, Calif.).

Infectious clone construction and virus recovery. An infectious molecular cDNA clone of MuV-UC was produced by first reverse transcribing RNA isolated from MuV-UC virus, and then amplifying overlapping regions of the genome using PCR, and the PCR products were sequentially cloned into the pSMART vector (Lucigen Corp, WI). The rMuV-UC full-length genome was assembled between artificially introduced SnaBI and Notl restriction sites. Additional restriction sites were generated in the genome by overlapping PCR. The enhanced green fluorescent protein (eGFP) ORF was amplified from plasmid pIRES2-EGFP (Promega Corp., Madison, Wis.). A translation unit that comprises the transcription start and end signals of mumps P and M intergenic region. were introduced flanking the GFP coding region was constructed using overlapping PCR, and cloned between the G and L genes using introduced unique NheI and SmaI restriction sites. A T7 promoter and terminator were introduced at the beginning and end of the genome respectively A hepatitis delta virus ribozyme (HDV) was added to the 5'terminus to get the precise virus genome upon transcription (Ammayappan et al., 2013 J Virol 87:3217-3228). This completes the full-length infectious molecular clone of MuV-UC in plasmid pMuV-UC-GFP. GFP was replaced with firefly luciferase or human sodium iodide symporter (NIS) ORFs by PCR to create pMuV-UC-LUC and pMuV-UC-NIS plasmids respectively. pMuV-UC-mIFNβ-GFP was created by introduction of mIFNβ between M and F genes using Sbfl and MluI restriction sites. pMuV12 UC-L13328-GFP is created by overlapping PCR using primers with mutated nucleotides. To complete the MuV-UC reverse genetics system, three helper plasmids were constructed to express the MuV-UC N, P and L proteins: pMuV-UC-N, pMuV-UC-P, and pMuV-UC-L. These sequences were PCR amplified and cloned into pCI mammalian expression vector (Promega Corp., Madison, Wis.) between NheI and NotI restriction sites.

Recombinant MuV-UCs (rMuV-UCs) were rescued as follows. BHK cells were plated at a density of 1×10⁶ cells/well in 6-well plates. The cells were infected with the VTF-7 of vaccinia virus encoding the T7 polymerase gene at a multiplicity of infection (MOI) of 10. After an hour, the supernatant containing the vaccinia virus was removed, and the cells were transfected with 5 μg pMuV, 0.5 μg pMuV-UC-N, 0.05 μg pMuV-UC-P, and 0.2 μg pMuV-UC-L using 12 μl of Fugene 6 transfection reagent (Promega, Wis.) in Opti-MEM according to the manufacturer's instructions. The cells were incubated overnight at 37° C., and then the medium replaced with growth medium. After 7 days, the culture medium was harvested, filtered twice through a 0.2 μm filter, and the filtrate overlaid onto Vero cells for virus amplification. Five days later, the culture medium was harvested and clarified by low-speed centrifugation, and the infectious mumps virus stock titrated on fresh Vero cells. When necessary the recombinant viruses were further passaged on vero cells to amplify the viral titer. Rescued viruses were titered using a standard plaque assay described earlier (Ammayappan et al., 2013 J Virol 87:3217-3228). The identities of the recombinant viruses were verified by determining the nucleotide sequence of cDNA products synthesized using RT-PCR and viral genomic RNA.

Growth curve analysis. Growth curve analysis was carried out as described earlier (Ammayappan et al., 2013 J Virol 87:3217-3228). For multistep growth curves, Vero cells were incubated with rMuV at an MOI of 0.01 for 1 hour at 37° C. Following this incubation, supernatant was removed, the monolayer was washed, and fresh growth medium was added. Supernatant was collected at predetermined time points (24, 48, 72, 96, and 120 hours), and the virus titer was determined in a standard plaque assay.

Immunofluorescence. Fluorescence microscope was used to analyze and image green fluorescent protein (GFP)-expressing cells.

In vitro assays. To measure in vitro radio-iodide uptake, cells were incubated in Hanks-buffered salt solution with 10 mM HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid, pH 7.3) in the presence of radio-labeled NaI (I¹²⁵ at 1×10⁵ cpm) +/− 100 uM potassium perchlorate (KClO₄). After 1 hour incubation, the medium was removed and cells were washed twice. The remaining cells were re-suspended in sodium chloride. Radioactivity was measured in a gamma-counter. The assays were performed in triplicate and the means plotted. Interferon-β secretion in supernatant of infected cells was determined using enzyme-linked immunosorbent assay against murine IFNβ (VeriKine Mouse Interferon Beta ELISA Kit, PBL, N.J.). Luciferase production was measured using Luciferase Assay Systems kit (Promega, Wis.) according to the manufactures protocol.

In vivo experiments. All animal protocols were reviewed and approved by the Mayo Clinic Institutional Care and Use Committee. BALB/c mice, females, 4 to 6 weeks old, were purchased from Jackson Laboratories. Mice were implanted with 5×10⁶ mouse colon carcinoma (CT-26-LacZ) cells in the right flank. When tumors reached an average size of 0.2 to 0.5 cm3, mice were treated with a single intravenous injection of mumps virus via tail vein. Tumor volume was measured using a hand-held caliper. The mice were monitored daily until the end of the study (60 days) or when they reached the euthanasia criteria. The euthanasia criteria were as follows: clinical signs of neurotoxicity, tumor ulceration, tumor volume greater than 2000 mm³, weight loss greater than 10%, or mice unable to gain access to food or water.

NCr nude mice, 4-6 weeks old, were purchased from Taconic (Hudson, N.Y.). One day before implantation of xenografts, mice were whole body irradiated (2 Gy). The next day, 5×10⁶ KAS 6/1 cells were implanted subcutaneously in the right flank. When tumors reached a volume of 100 mm³, 1×10⁷ PFU of mumps virus, or an equal volume of saline, was injected intravenously via tail vein. The rest of the study was conducted as the Balb/C mice experiment.

A/J mice females, 4 to 6 weeks old, were purchased from Jackson Laboratories. Mice were implanted with 5×10⁶ mouse neuroblastoma (N2A) cells in the right flank. When tumors reached an average size of 0.5 cm³, mice were treated with a single intravenous injection of mumps viruses (1×10⁷ PFU) via tail vein. The rest of the study was conducted as above.

Immunohistochemistry. Harvested tumors were frozen in optimal cutting medium (OCT) for cryo-sectioning. Tumor sections were analyzed by immunofluorescence for mumps virus antigens using a polyclonal rabbit anti-MuV-U serum, followed by Alexa-labeled anti-rabbit IgG secondary antibody (Life Technologies, N.Y.), and cellular nuclei were stained with Hoechst 33342 (Life Technologies, N.Y.).

Statistical analyses. An unpaired two-tailed Student t test was carried out to compare the values. Survival curve analysis was done using the Prism 4.0 program (GraphPad Software, San Diego, Calif.). Survival curves were plotted according to the Kaplan-Meier method, and survival function across treatment groups was compared using log rank test analyses.

RESULTS

Mumps virus Urabe strain

An aliquot of the mumps virus Urabe strain used in oncolytic virotherapy human clinical trials in Japan in the 1970's and 1980's was obtained. A representative clone, MuV-U Clone 1-C-3 (MuV-UC-WT) was isolated, characterized, and used in this study. One unique aspect of this MuV-UC virus stock was the minimal amplification in cultured cells that may have minimized the attenuation from the original patient isolate.

The development of a reverse genetics system based on mumps virus Urabe strain

A reverse genetics platform based on the nucleotide sequence of the MuV-UC isolate was constructed initially with an additional transcription unit containing the GFP coding sequence flanked by unique restriction enzyme cloning sites between MuV-UC genes FIN and L, in a plasmid vector pMuV-UC-GFP. Negative-strand RNA can be synthesized using T7 polymerase and the T7 transcription elements flanking the MuV-UC genome along with three MuV-UC based helper plasmids expressing MuV-UC N, P and L proteins. BHK cells infected with a vaccinia virus vector encoding the T7 polymerase were then transfected with the infectious MuV-UC plasmid along with the three helper plasmids to rescue recombinant virus. After successful rescue in BHK cells, the recombinant MuV-UC virus was further propagated in Vero cells to produce virus stocks (FIG. 5a ). When growth potential of recombinant mumps virus expressing GFP was compared with wild-type virus, it showed better growth rate (FIG. 5b ).

To test the genomic stability and transgene expression abilities of the recombinant MuV-UC platform, several other recombinant viruses with different useful transgenes for in vivo bio-distribution and efficacy studies were constructed (FIG. 6a ). The GFP coding region was replaced with the luciferase gene (rMuV-UC-LUC), or the human sodium iodide symporter (NIS) gene (rMUV-UC-NIS). Whether two transgenes could be inserted and expressed from the rMuV-UC platform was also tested by adding an additional transgene, mouse interferon beta (mIFNβ), in between M and F genes of rMuV-UC-GFP creating rMuV-UC-mIFNβ-GFP that should express both the mIFNβ and GFP. All the recombinant mumps viruses replicated well on Vero cells (FIG. 6b ). The rMuV-UC-mIFNβ-GFP with two transgenes replicated to a lower titer compare to viruses with single transgenes. All transgenes delivered by the recombinant mumps viruses were well expressed (FIG. 6C-E).

Oncolytic activity of rMuV-UC-GFP replication in tumor cell lines

Since oncolytic virotherapy not only expects the virus to directly kill tumor cells but then cause a unique immune response to the tumor to completely cure the patient, efficacy models that can evaluate both strategies of this two-pronged therapeutic approach are best. Therefore, while we want to know the efficacy of mumps virus for treating human tumors, human tumor xenografts in nude mice can only evaluate the virus killing therapeutic component. Since some syngeneic mouse tumors models respond similarly to their human tumor counterparts, the infectivity and oncolytic activity of the rMuV-UC-GFP virus on a variety of human and mouse tumor cell lines was investigated. The oncolytic efficacy of rMuV-UC-GFP in various human cancer cell lines was tested (FIG. 7A). The human tumor cell lines were infected with rMuV-UC-GFP at an M.O.I. 1.0 and analyzed 5 days later by fluorescence microscopy for GFP expression. This analysis demonstrated that mumps virus could infect most human tumor cell lines tested.

Most of the mouse tumor cell lines are non-permissive to robust rMuV-UC-GFP virus infection and replication, with only the N2A neuroblastoma cell line and the CT-26-LacZ colon cancer cell lines showing significant numbers of GFP positive cells (FIG. 7B). Both the N2A and CT-26-LacZ tumor lines permitted some rMuV-UC-GFP replication but at significantly lower titers compared to rMuV-UC-GFP replication on human Kas 6/1 tumor cells (FIG. 7C). Significant cell killing was observed in most human tumor lines tested, however the extent as well as the rate of cell killing can differ substantially between individual tumor cell lines (FIG. 8). Very little cell killing was observed in the infected mouse tumor lines with the best in the N2A and CT-26-LacZ by day 7, where the mumps virus replicated relatively well.

Since the neurovirulence studies of mumps virus has been carried out in rat models, the infectivity and replication of rMuV-UC-GFP in some of the rat tumor cell lines was tested. C6 and RG2 are two rat glioma tumor cell lines, and were infected with mumps virus at different MOI. RG2 glioma cells were more permissive to MuV infection compared to C6 cells (FIG. 9A). Mumps virus multiplies better in RG2 cells reaching its peak titer (6×10⁵ pfu/mL) at 72 hours post-infection (FIG. 9B). The titer produced by RG2 cells is almost two logs higher than C6 cells but more than a log lower than Vero cells. In correlation with the higher rMuV-UC-GFP replication in RG2 cells compared to C6 cells, up to 60% of the RG2 cells were killed by the mumps virus compared to just 10-20% of C6 cells as determined by MTS assay, confirmed the higher infectivity in RG2 cells (FIG. 9C).

Modulation of interferon pathway and its effect on mumps virus replication

It has been shown that mumps virus infection in non-permissive rodent cells resulted in abortive infection (Yamada et al., 1984 J Gen Virol 65:973-980). This may be caused by the presence of antiviral machinery or due to inefficient penetration of virus into the cell. Since interferon is one of the obstacles that could prevent MuV replication, some of the less permissive cell lines were treated with Janus kinase inhibitor, Ruxolitinib (Escobar-Zarate et al., 2013 Cancer Gene Ther 20:582-589), and then infected the treated cells with rMuV-UC-GFP. The Ruxolitinib treatment increased the viral infection significantly in rat glioma (C6), mouse lung carcinoma (LLC) cells and also to some extent in CT-26 colon carcinoma cells, but not in plasmacytoma (MPC11) and human myeloma (MM1) cells (FIG. 10). This suggests that individual cell lines not only differ in the innate immune defense but also employ more than one mechanism to restrict viral replication. So the low infectivity of MuV in mouse tumor cells may be the result of multiple cellular factors rather than single one that control different steps in the mumps virus life-cycle.

Oncolytic efficacy of mumps viruses in immunocompetent mouse models

To test the oncolytic activity of mumps virus in immunocompetent mouse models, pilot preliminary studies using the two relatively permissive mouse cancer cell lines to mumps virus infection, colon carcinoma (CT-26-LacZ) and neuroblastoma (N2A), were conducted. These tumor cells were implanted into the flanks of syngeneic mice, Balb/C and A/J respectively. Once the tumors reached a significant size, mumps viruses were administered intravenously through the tail vein. In CT-26-LacZ model, groups of mice were treated with rMuV-UC-GFP at 10⁶ and 10⁷, rMuV UC-LUC at 10⁷, MuV-UC at 10⁷, and a saline control. Some of the mice with CT-26-LacZ tumors treated with rMuV-UC-LUC or MuV-UC virus had delay in their tumor growth and had better overall survival with one rMuV-UC-LUC treated mouse and two MuV-UC virus treated mice having a complete response (FIG. 11). However, immunohistochemical analysis of tumor tissue on day 14 doesn't show any mumps virus positive staining and also the luciferase imaging on day 7 and 14 yielded no positive signal (Data not shown). This suggests that there may be an involvement of immune system in tumor suppression.

Mutating a single amino acid in polymerase gene increased the replication rate of mumps virus (nt13328, aa N to H). When this virus was compared with MuV-UC-WT and rMuV-UC-GFP, no significance difference was observed in oncolytic activity in in vitro studies (FIG. 12). This virus (rMuV-UC1 L₁₃₃₂₈-GFP) was used for the rest of the animal studies. In the N2A model, mice were treated with rMuV UC-LUC, rMuV-UC-L₁₃₃₂₈-GFP, MuV-UC, and equal amount of saline. No significant anti-tumor activity was seen in the N2A tumor model possibly due to the aggressive nature of N2A tumor with most of the mice requiring sacrifice around 10 days post-infection (FIG. 13). However, one mouse survived in rMuV-UC-L₁₃₃₂₈-GFP treated group.

Oncolytic efficacy of mumps virus in human myeloma model

In order to initially assess the antitumor activity of the mumps viruses in vivo in a human myeloma model, human myeloma tumor cells (Kas6/1) were implanted into the flanks of nude mice. Once the tumor reached an appreciable size, 10⁷ PFU of rMuV-UC-LUC, rMuV-UC-L₁₃₃₂₈-GFP, MuV-UC or saline were injected intravenously thorough the tail vein, and the mice observed for 60 days (FIG. 14). Some variability was seen in the growth of the individual tumor xenografts in saline treated animals, with 4 of 5 animals succumbing to tumor load by 60 days. This variability was seen in all four groups and prevented the survival results from reaching statistical significance. However, the data clearly shows the MuV-UC isolate suppressed the tumor growth in all five animals, with one animal having a complete response. The results from mice treated with the recombinant viruses were promising with one complete response and possibly two tumors controlled when treated with rMuV-UC-LUC, while two animals had a complete response to treatment with rMuV-UC-L₁₃₃₂₈- GFP. To confirm virus replication, tumors were harvested from mice on day 7 and day 12 after virus administration and analyzed for mumps virus antigens. All tumors were positive for mumps viral proteins on day 7 and showed increased staining on day 12. MuV-UC treated tumors having comparatively better infectivity and spread relative to the tumors treated with the recombinant mumps viruses (FIG. 15). Since these studies involved single administration of mumps virus, other treatment regimens could possibly improve oncolytic efficacy significantly.

Conclusions

These results demonstrate that recombinant MuV can infect wide variety of human tumor cells, and that MuV show significant tumor suppression, delay in tumor growth, and also statistically significant increase in survival rate.

OTHER EMBODIMENTS

It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 

What is claimed is:
 1. A recombinant mumps virus (MuV) having oncolytic anti-cancer activity.
 2. The recombinant MuV of claim 1, wherein said recombinant MuV is a replication competent MuV.
 3. The recombinant MuV of claim 1, wherein said recombinant MuV comprises a modification in an RNA polymerase large (L) subunit coding sequence.
 4. The recombinant MuV of claim 3, wherein said modification in an RNA polymerase large (L) subunit coding sequence comprises an A to C substitution at nucleotide
 13328. 5. The recombinant MuV of claim 3, wherein said modification in an RNA polymerase large (L) subunit coding sequence encodes a modified RNA polymerase large (L) subunit protein
 6. The recombinant MuV of claim 5, wherein modified RNA polymerase large (L) subunit protein comprises an N to H substitution at amino acid
 1631. 7. A method for treating a patient having cancer, the method comprising: administering to the patient a recombinant mumps virus (MuV) having oncolytic anti-cancer activity.
 8. The method of claim 7, wherein the cancer is a blood cancer selected from leukemia, lymphoma, or myeloma.
 9. The method claim 8, wherein the blood cancer is myeloma.
 10. The method of claim 7, wherein the cancer is a carcinoma selected from prostate cancer, breast cancer, hepatocellular carcinoma, lung cancer, or colorectal carcinoma.
 11. The method of claim 10, wherein the carcinoma is colorectal carcinoma.
 12. The method of claim 7, wherein said recombinant MuV is a replication competent MuV.
 13. The method of claim 7, wherein said recombinant MuV comprises a modification in an RNA polymerase large (L) subunit coding sequence.
 14. The method of claim 13, wherein said modification in an RNA polymerase large (L) subunit coding sequence comprises an A to C substitution at nucleotide
 13328. 15. The method of claim 13, wherein said modification in an RNA polymerase large (L) subunit coding sequence encodes a modified RNA polymerase large (L) subunit protein.
 16. The method of claim 15, wherein modified RNA polymerase large (L) subunit protein comprises an N to H substitution at amino acid
 1631. 17. The method of claim 7, further comprising administering ruxolitinib.
 18. An expression construct comprising a nucleotide sequence encoding a recombinant MuV having oncolytic anti-cancer activity.
 19. The expression construct of claim 18, wherein said recombinant MuV is a replication competent MuV.
 20. The expression construct of claim 18, wherein said recombinant MuV comprises a modification in an RNA polymerase large (L) subunit coding sequence.
 21. The expression construct of claim 20, wherein said modification in an RNA polymerase large (L) subunit coding sequence comprises an A to C substitution at nucleotide
 13328. 22. The expression construct of claim 20, wherein said modification in an RNA polymerase large (L) subunit coding sequence encodes a modified RNA polymerase large (L) subunit protein.
 23. The expression construct of claim 22, wherein modified RNA polymerase large (L) subunit protein comprises an N to H substitution at amino acid
 1631. 24. A method for treating a patient having cancer, the method comprising: administering to the patient an expression construct comprising a nucleotide sequence encoding a recombinant mumps virus (MuV) having oncolytic anti-cancer activity.
 25. The method of claim 24, wherein the cancer is a blood cancer selected from leukemia, lymphoma, or myeloma.
 26. The method claim 25, wherein the blood cancer myeloma.
 27. The method of claim 24, wherein the cancer is a carcinoma selected from prostate cancer, breast cancer, hepatocellular carcinoma, lung cancer, or colorectal carcinoma.
 28. The method of claim 27, wherein the carcinoma is colorectal carcinoma.
 29. The method of claim 24, wherein said recombinant MuV is a replication competent MuV.
 30. The method of claim 24, wherein said recombinant MuV comprises a modification in an RNA polymerase large (L) subunit coding sequence.
 31. The method of claim 30, wherein said modification in an RNA polymerase large (L) subunit coding sequence comprises an A to C substitution at nucleotide
 13328. 32. The method of claim 30, wherein said modification in an RNA polymerase large (L) subunit coding sequence encodes a modified RNA polymerase large (L) subunit protein.
 33. The method of claim 32, wherein modified RNA polymerase large (L) subunit protein comprises an N to H substitution at amino acid
 1631. 34. The method of claim 24, further comprising administering ruxolitinib. 